Hydroclimatic vulnerability of peat carbon in the central Congo Basin.

The forested swamps of the central Congo Basin store approximately 30 billion metric tonnes of carbon in peat1,2. Little is known about the vulnerability of these carbon stocks. Here we investigate this vulnerability using peat cores from a large interfluvial basin in the Republic of the Congo and palaeoenvironmental methods. We find that peat accumulation began at least at 17,500 calibrated years before present (cal. yr BP; taken as AD 1950). Our data show that the peat that accumulated between around 7,500 to around 2,000 cal. yr BP is much more decomposed compared with older and younger peat. Hydrogen isotopes of plant waxes indicate a drying trend, starting at approximately 5,000 cal. yr BP and culminating at approximately 2,000 cal. yr BP, coeval with a decline in dominant swamp forest taxa. The data imply that the drying climate probably resulted in a regional drop in the water table, which triggered peat decomposition, including the loss of peat carbon accumulated prior to the onset of the drier conditions. After approximately 2,000 cal. yr BP, our data show that the drying trend ceased, hydrologic conditions stabilized and peat accumulation resumed. This reversible accumulation-loss-accumulation pattern is consistent with other peat cores across the region, indicating that the carbon stocks of the central Congo peatlands may lie close to a climatically driven drought threshold. Further research should quantify the combination of peatland threshold behaviour and droughts driven by anthropogenic carbon emissions that may trigger this positive carbon cycle feedback in the Earth system.

Search by the SENSEI Experiment for Millicharged Particles Produced in the NuMI Beam.

Millicharged particles appear in several extensions of the standard model, but have not yet been detected. These hypothetical particles could be produced by an intense proton beam striking a fixed target. We use data collected in 2020 by the SENSEI experiment in the MINOS cavern at the Fermi National Accelerator Laboratory to search for ultrarelativistic millicharged particles produced in collisions of protons in the NuMI beam with a fixed graphite target. The absence of any ionization events with 3 to 6 electrons in the SENSEI data allow us to place world-leading constraints on millicharged particles for masses between 30 to 380 MeV. This work also demonstrates the potential of utilizing low-threshold detectors to investigate new particles in beam-dump experiments, and motivates a future experiment designed specifically for this purpose.

Simulating carbon accumulation and loss in the central Congo peatlands.

Peatlands of the central Congo Basin have accumulated carbon over millennia. They currently store some 29 billion tonnes of carbon in peat. However, our understanding of the controls on peat carbon accumulation and loss and the vulnerability of this stored carbon to climate change is in its infancy. Here we present a new model of tropical peatland development, DigiBog_Congo, that we use to simulate peat carbon accumulation and loss in a rain-fed interfluvial peatland that began forming ~20,000 calendar years Before Present (cal. yr BP, where 'present' is 1950 CE). Overall, the simulated age-depth curve is in good agreement with palaeoenvironmental reconstructions derived from a peat core at the same location as our model simulation. We find two key controls on long-term peat accumulation: water at the peat surface (surface wetness) and the very slow anoxic decay of recalcitrant material. Our main simulation shows that between the Late Glacial and early Holocene there were several multidecadal periods where net peat and carbon gain alternated with net loss. Later, a climatic dry phase beginning ~5200 cal. yr BP caused the peatland to become a long-term carbon source from ~3975 to 900 cal. yr BP. Peat as old as ~7000 cal. yr BP was decomposed before the peatland's surface became wetter again, suggesting that changes in rainfall alone were sufficient to cause a catastrophic loss of peat carbon lasting thousands of years. During this time, 6.4 m of the column of peat was lost, resulting in 57% of the simulated carbon stock being released. Our study provides an approach to understanding the future impact of climate change and potential land-use change on this vulnerable store of carbon.

Age, extent and carbon storage of the central Congo Basin peatland complex.

Peatlands are carbon-rich ecosystems that cover just three per cent of Earth's land surface, but store one-third of soil carbon. Peat soils are formed by the build-up of partially decomposed organic matter under waterlogged anoxic conditions. Most peat is found in cool climatic regions where unimpeded decomposition is slower, but deposits are also found under some tropical swamp forests. Here we present field measurements from one of the world's most extensive regions of swamp forest, the Cuvette Centrale depression in the central Congo Basin. We find extensive peat deposits beneath the swamp forest vegetation (peat defined as material with an organic matter content of at least 65 per cent to a depth of at least 0.3 metres). Radiocarbon dates indicate that peat began accumulating from about 10,600 years ago, coincident with the onset of more humid conditions in central Africa at the beginning of the Holocene. The peatlands occupy large interfluvial basins, and seem to be largely rain-fed and ombrotrophic-like (of low nutrient status) systems. Although the peat layer is relatively shallow (with a maximum depth of 5.9 metres and a median depth of 2.0 metres), by combining in situ and remotely sensed data, we estimate the area of peat to be approximately 145,500 square kilometres (95 per cent confidence interval of 131,900-156,400 square kilometres), making the Cuvette Centrale the most extensive peatland complex in the tropics. This area is more than five times the maximum possible area reported for the Congo Basin in a recent synthesis of pantropical peat extent. We estimate that the peatlands store approximately 30.6 petagrams (30.6 × 1015 grams) of carbon belowground (95 per cent confidence interval of 6.3-46.8 petagrams of carbon)-a quantity that is similar to the above-ground carbon stocks of the tropical forests of the entire Congo Basin. Our result for the Cuvette Centrale increases the best estimate of global tropical peatland carbon stocks by 36 per cent, to 104.7 petagrams of carbon (minimum estimate of 69.6 petagrams of carbon; maximum estimate of 129.8 petagrams of carbon). This stored carbon is vulnerable to land-use change and any future reduction in precipitation.

Carpal tunnel syndrome and Raynaud's phenomenon: a narrative review.

BACKGROUND: Raynaud's phenomenon (RP) is a recognized symptom associated with carpal tunnel syndrome (CTS) and is also the vascular manifestation of hand arm vibration syndrome (HAVS). The symptoms of HAVS and CTS are such that there is a significant possibility of misdiagnosis and an incorrect attribution of vascular and sensory symptoms. An understanding of the relationship between RP and CTS is essential when undertaking health surveillance of vibration-exposed workers presenting with combined vascular and sensory symptoms. AIMS: To clarify the relationship between CTS and Raynaud's phenomenon. METHODS: A systematic search was undertaken of studies that reviewed links between CTS and Raynaud's phenomenon (RP). RESULTS: A total of 4170 papers were identified, with 21 articles that were then reviewed in full, including 1 meta-analysis of 8 studies. Eighteen papers, not included in the meta-analysis, were found including 3 case control studies, 9 case reports, 2 prospective studies and 4 retrospective reviews. Papers were reviewed on the basis of the diagnostic criteria used for CTS and RP. Our review of the literature confirms a substantial body of evidence of a relationship between RP and CTS. CONCLUSIONS: It is recommended that assessment of vibration exposed individuals who report concurrent RP and separate sensory symptoms suggestive of, or compatible with CTS, should formally exclude CTS before attributing symptoms to HAVS.

CRAFTING THE MICROWORLD: HOW ROBERT HOOKE CONSTRUCTED KNOWLEDGE ABOUT SMALL THINGS.

This paper investigates the way in which Robert Hooke constructed his microscopical observations. His Micrographia is justifiably famous for its detailed engravings, which communicated Hooke's observations of tiny nature to his readers, but less attention has been paid to how he went about making the observations themselves. In this paper I explore the relationship between the materiality of his instrument and the epistemic images he produced. Behind the pictures lies an array of hidden materials, and the craft knowledge it took to manipulate them. By investigating the often counter-theoretical and conflicting practices of his ingenious microscope use, I demonstrate the way in which Hooke crafted the microworld for his readers, giving insight into how early modern microscopy was understood by its practitioners and audience.

Bears in Eden, or, this is not the garden you're looking for: Margaret Cavendish, Robert Hooke and the limits of natural philosophy.

This paper investigates Margaret Cavendish's characterization of experimental philosophers as hybrids of bears and men in her 1666 story The Description of a New World, Called the Blazing World. By associating experimental philosophers, in particular Robert Hooke and his microscope, with animals familiar to her readers from the sport of bear-baiting, Cavendish constructed an identity for the fellows of the Royal Society of London quite unlike that which they imagined for themselves. Recent scholarship has illustrated well how Cavendish's opposition to experimental philosophy is linked to her different natural-philosophical, political and anthropological ideas. My contribution to this literature is to examine the meanings both of bears in early modern England and of microscopes in experimental rhetoric, in order to illustrate the connection that Cavendish implies between the two. She parodied Hooke's idea that his microscope extended his limited human senses, and mocked his aim that by so doing he could produce useful knowledge. The bear-men reflect inhuman ambition and provide a caution against ignoring both the order of English society and the place of humans in nature.

A qualitative meta-synthesis of evidence (meta-ethnography) exploring the personal experiences of gastrostomy tube in neurodegenerative diseases: a case of motor neurone disease.

PURPOSE: The lived experiences of a gastrostomy tube (GT) in adults with neurodegenerative diseases (NDDs) are not well understood. The aim of this qualitative meta-synthesis was to review and synthesise the available evidence to inform clinical practice and identify research gaps. METHODS: Meta-ethnographic synthesis of qualitative studies was conducted with systematic searching of eight databases from inception to March 2021. Qualitative studies reporting personal experiences of GTs in adults with NDDs were identified. New theories were developed during translation of concepts from each study and combined as a "line-of-argument" synthesis. Patient and public involvement was incorporated as two of the authors are living with an NDD and a GT. RESULTS AND CONCLUSIONS: Of 2863 unique records identified, only nine fulfilled the review criteria. All studies recruited participants with motor neurone disease (MND); no other NDDs were represented. Two main themes emerged: decision making and living with GT. Decision making was the predominant theme and data regarding living with GT were sparse. There is limited research on the lived experience of a GT in adults with NDDs. The lived experience of GT in MND is complex and individualised. Future research is indicated to inform clinical practice.Implications for rehabilitationEvidence related to the lived experiences of gastrostomy tube (GT) in neurodegenerative diseases (NDDs) is lacking especially in relation to the time after GT insertion.Decision making in relation to GT is a complex and individualised psychological process for some people, while others perceive no decisional conflict.Support from healthcare professionals is crucial during the decision-making time and should not cease after GT insertion.Support from healthcare professionals can help resolve any clinical complications and also incorporate GT into everyday routines.Healthcare professionals should be aware that their views on the benefits and problems related to GT may differ to those of individuals with a NDD.

Use of Doppler in the diagnosis of hypothenar hammer syndrome.

BACKGROUND: Hand-arm vibration syndrome (HAVS) includes a spectrum of vascular, neurological and musculoskeletal symptoms resulting from exposure to vibrating tools. Hypothenar hammer syndrome (HHS) is a lesion of the ulnar artery as it courses adjacent to the hamate bone and results from either single or repeated episodes of trauma to the hypothenar eminence. There is a need to distinguish symptoms of HHS from those of classical HAVS since precise diagnosis may alter both the clinical and occupational management of the affected employee. AIMS: To highlight the value of simple Doppler assessments of the palmar blood flow to distinguish the condition of HHS from 'classical' HAVS. METHOD: Among patients assessed for HAVS by the authors during 2006, three were identified as potentially having HHS. Doppler ultrasound of the palmar arches with and without ulnar arterial occlusion was used. RESULT: We report three cases in which Doppler ultrasound assessment supports a diagnosis of HHS. CONCLUSIONS: It is our recommendation that such Doppler assessments should form part of the clinical assessment of workers being assessed in connection with exposure to hand-transmitted vibration and in whom symptoms are present that are not typical of 'classical HAVS', particularly where there is a history of possible hypothenar trauma.